Ask the Experts Metals

Can you eliminate intergranular oxidation of your steel parts during carburizing?

Zbigniew Zurecki
Research Associate

Internal or intergranular oxidation (IGO) occurs during carburization using endothermic or dissociated methanol atmospheres. Metals processors who eliminate or at least minimize IGO can gain substantial benefits including reduced grinding after carburizing, shortened carburizing cycles, and an improved fatigue-life of gears, shafts and other machine parts.

Preventing oxidation of more reactive steel elements (Mn, Si, and Cr) can be achieved by carburizing in dry hydrocarbon atmospheres that contain no CO additions. Fortunately new technology offers an easier, less costly retrofit alternative. It has been shown during carburizing in the traditional integral quenching and pit furnaces, that an atmosphere of nitrogen containing just a couple percent of natural gas and/or propane produces the same IGO-free, hard cases as the vacuum carburizing process. These N2-HC atmosphere systems have been installed on existing, ambient-pressure furnaces, and industrial tests are in progress.

If you are interested in the mitigating IGO and/or in the low-cost, atmospheric-pressure, N2-HC atmosphere solutions, please call Air Products at 800-654-4567.

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